This laboratory core will support all five preclinical projects and the clinical Phase I clinical trial of this Program Project. Each specific aim of this core is designed to test for specific parameters (chemokine/cytokine expression) or produce products (5- helix fusion inhibitor) key to the success of each project. However, this core will only support but not perform the hypothesis-driven research detailed in each project. Specific Aim 1 will involve collecting and processing clinical samples for genetic analyses of CCR5 receptor and promoter polymorphisms. Project 6 will obtain approximately 150 samples from HIV-negative individuals in the U.S. and Uganda. This laboratory core will process and ship these blood samples to the Zimmerman?s laboratory at Case Western Reserve University for genetic screens of CCR5 polymorphisms. This will be preformed only in Year 01 of the Program Project. Specific Aim 2 will involve collection, processing, and analysis of vaginal lavage and blood samples from the Phase I clinical trial. Samples will be collected from U.S. and Ugandan participants starting at the end of Year 01 of Project 6 and coinciding with the end of Specific Aim 1. Specific Aim 2 will analyze cytokine/chemokine levels in the vaginal lavage fluid and various markers (e.g., CCR5, CD4, CDI4) on surface of vaginal lavage cells. In Years 04 and 05 of Project 6, HIV-1 will be isolated from the genital tract and blood of HIV-infected participants treated with the PSCRANTES vaginal microbicide. Vaginal- and blood-derived HIV-1 isolates will then be used in drug sensitivity assays. Specific Aim 3 will focus on the production and purification of S-helix. This aim will involve fermentation of bacteria expressing the 5-helix6H fusion inhibitor and purification of Histagged protein by Ni chelate chromatography. C-34 will be produced as synthetic peptide Project 1. Both fusion inhibitors will be used in all preclinical projects as anti-HIV-1 agents and in combination with PSC-RANTES. Finally, development of assays to measure levels of fusion inhibitors in biologic samples will be performed in Specific Aim 4. Pharmacokinetic studies on the half-life of fusion inhibitors in blood and genital tract will be analyzed in samples from participants enrolled in Phase I microbicide trial.